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THURSDAY, Aug. 16, 2012 (HealthDay News) —Elderly people who experience no decline in memory have certain brain characteristics that differ from their peers who show more typical age-related memory loss, new research reveals.

Scientists from Northwestern University's Cognitive Neurology and Alzheimer's Disease Center identified 12 people aged 80 and older who did as well or better on memory tests as people who were 20 to 30 years younger. Researchers dubbed them "SuperAgers."

MRI scans showed that the cortex of SuperAgers was thicker than a comparison group of people aged 80 and older. The cortex is the outer layer of the brain involved in memory, attention and other thinking abilities.

Brain scans also showed that people in their 80s and 90s who exhibited more typical memory declines (though not the marked decline associated with Alzheimer's disease or other thinking impairments, researchers said) had a thinner cortex.

"The SuperAgers looked more like the middle-aged controls, despite being 20 to 30 years older," Rogalski said. "We didn't see any significant atrophy or brain cell loss."

The study is published in the current issue of the Journal of the International Neuropsychological Society.

Some degree of forgetfulness is a common complaint among the elderly, Rogalski said. "These complaints are so widespread that it's come to be thought of as a normal part of aging," she noted.

Many prior studies have shown that brain atrophy and loss of thinking abilities go hand in hand, said Dr. Russell Swerdlow, director of the Alzheimer's Disease Center at the University of Kansas.

This study is unique in that it starts with people with exceptionally good memories for their age, and then looks at what makes their brains different, he said.

He noted, however, that the study shows a correlation between good memories in later life and a thicker cortex and larger brain volume, but it doesn't show cause-and-effect. What is unknown is if retaining brain volume protects thinking abilities, or if maintaining thinking abilities protects brain volume.

"It could be that those whose brains are better 'built to last' structurally are probably those brains that are better built to last from a functional perspective, or that those who are exercising their brains may have less atrophy," he said.

At the same time, SuperAgers also had a larger cingulate cortex, another brain region also involved in attention and memory, than even the middle-aged participants. What's unknown is if SuperAgers were born with a more prominent cingulate cortex or if that region resisted atrophy in later life, according to the study.

With studies like this, one thing people want to know is what it takes to be among the SuperAgers. Unfortunately, there aren't yet any clear answers, Rogalski said.

"Genetics are likely to play a role. And, in general, a healthy lifestyle is supportive of good memory," Rogalski said. "But in our experience, some of our SuperAgers have been smoking a pack of cigarettes for the last 20 years. Others have never touched them. Some go to the gym three to five days a week. Others don't exercise. Some are still working and others have never worked. It seems there might be more than one route to being a SuperAger."